I did some HDR images inside of the church that I attend using natural lighting. The images worked out very well, I thought. Definitely use any ambient light coming in through any windows. I'm not sure about using a flash for this but something tells me that the pros use them when they need to.
I would take shots from the viewpoint of the renter. From the head of the bed, from the vicinity of the desk/chair/table area, looking in through the entrance, view out the window including the window framing, etc.,. I'm definitely no architectural photographer but those are just some things that come to mind....and my post gives you a small bump back up top.
Set up your camera on a tripod and experiment...trial and error will definitely get you there and I'm sure you'll be getting more advice from folks more knowledgeable than me.
Best wishes on the photos and the renters,